1. Field of the Invention
The present application relates to an amplifier.
2. Background Arts
In order to amplify power with a high gain and a high output, there is known an amplifier including a plurality of amplifying devices connected in series to each other. A Japanese Patent Application laid open No. 2000-77954A (JP 2000-77954A) discloses such an amplifier. In the amplifier, the plurality of amplifying devices connected in series to each other are integrated in one semiconductor chip. Further, the amplifier further includes three matching circuits. A first matching circuit is connected between an input terminal and an input port of a first-stage amplifying device. A second matching circuit is connected between an output port of the first-stage amplifying device and an input port of a second-stage amplifying device. A third matching circuit is connected between the output terminal and an output port of the second-stage amplifying device. Three matching circuits and one semiconductor chip are mounted on a common dielectric substrate.